Flu

Flu is an infectious and common viral illness spread by coughs and sneezes.

It's not the same as the common cold. Flu is caused by a different group of viruses. Symptoms tend to be more severe and last longer.

You can catch flu – short for influenza – all year round, but it is especially common in winter, which is why it is also known as "seasonal flu".

Flu causes a sudden high temperature, headache and general aches and pains, tiredness and a sore throat. You can also lose your appetite, feel nauseous and have a cough.

Flu symptoms can make you feel so exhausted and unwell that you have to stay in bed and rest until you feel better.

When to see a doctor

If you are otherwise fit and healthy, there is usually no need to see a doctor if you have flu-like symptoms.

The best remedy is to rest at home, keep warm and drink plenty of water to avoid dehydration.

You can take paracetamol or ibuprofen to lower a high temperature and relieve aches.

You should see a doctor if you have flu-like symptoms and you:

are aged 65 or over
are pregnant
have a long-term medical condition such as diabetes, heart disease, lung disease, kidney disease or a neurological disease
have a weakened immune system

This is because flu can be more serious for you, and your doctor may want to prescribe antiviral medication.

Antiviral medicine can lessen the symptoms of flu and shorten its duration, but treatment needs to begin soon after flu symptoms start for it to be effective.

Antibiotics are of no use in the treatment of flu because it is caused by a virus and not by bacteria.

How long does flu last?

If you have flu, you generally start to feel ill within a few days of being infected.

Symptoms peak after two to three days and you should begin to feel much better after a week or so, although you may feel tired for much longer.

You are usually infectious – that is, able to pass flu on to others – a day before your symptoms start and for a further five or six days. Children and people with weaker immune systems, such as cancer patients, may remain infectious for longer.

Elderly people and anyone with certain long-term medical conditions are more likely to have a bad case of flu, and are also more likely to develop a serious complication such as a chest infection.

In the UK, about 600 people a year die from a complication of seasonal flu. This rises to around 13,000 during an epidemic.

Read more about the complications of flu.

Preventing the spread of flu

The flu virus is spread in small droplets of fluid coughed or sneezed into the air by an infected person. These droplets can travel a metre or so and infect anyone within range who breathes them in.

Flu can also spread if someone with the virus transfers it on their fingers. For example, if you have flu and you touch your nose or eyes and then touch someone else, you may pass the virus on to them.

Similarly, if you have flu and touch hard surfaces such as door handles with unwashed hands, other people who touch the surface after you can pick up the infection.

The flu vaccine

A flu vaccine is available free on the NHS for:

anyone over the age of 65
pregnant women
children and adults with an underlying health condition (particularly long-term heart or respiratory disease)
children and adults with weakened immune systems

It is given as an annual injection to:

adults over the age of 18 at risk of flu (including everyone over 65)
children aged six months to two years at risk of flu

The flu vaccine is also given as an annual nasal spray to:

children aged two to 18 years at risk of flu
healthy children aged two, three and four years old

Despite popular belief, the flu vaccine cannot give you flu as it doesn't contain the active virus needed to do this.

The flu vaccine is available from October each year. If you think you need it, talk to your GP or practice nurse.

For more information on who should have the flu vaccine and how to get it, read the sections on the flu jab for adults, the flu jab for pregnant women and the children's flu vaccine.